1. Field of the Invention
The present invention relates to relevant fittings for a liner guideway and more particularly to a synchronous chain for a liner guideway whose head portion and tail portion are interconnected to avoid the interference, create guiding effect, effectively absorb size variation and have the practicality of mass production and assembly.
2. Description of the Prior Art
Nowadays, linear guideways are applied in the industry more and more, besides the high precision effect for the linear feed transmission, it further has the advantages of low frictional loss ratio, high energy-conversion ratio, low noise, and high stiffness not easy to damage etc. Hence, it is self-evident that the linear guideway is very important to the recent various industrial mechanisms.
In order to enable the rollers between the rail and the slide block to circulate endlessly and eliminate the stress therein, the recent linear guideway is provided with a chain retaining a plurality of rolling elements, and the rolling elements and the chain are made to perform a synchronous circulating motion between the slide block and the rail. However, different designs all have their respective shortcomings, accordingly, the recent industry emphasis is focused on how to research and develop the more competitive products from the lubricant units.
Frequently used conventional chains are shown in FIGS. 1-4; please refer to the following descriptions:
FIG. 1 shows an end-type conventional chain, both end portions 131 of the chain 13 are not connected, in such a manner, not only the end portions 131 are likely to protrude, but also a clearance exists between the two end portions 131, thereby, both end portions 131 of the chain 13 are likely to sway during the operation process, especially when passing the return path, both end portions of the synchronous chain 13 will sway violently, thus impacting the rail surface 14, or even the end portions of the synchronous chain 13 will be hooked by the patch 15 of the end cap. Consequently, the chain 13 can't move smoothly during operation process.
FIG. 2 shows a conventional chain 10 disclosed by JP Pat. No. 3,243,415, the conventional chain 10 is still provided with protruded end portions. Although both end portions of the chain 10 are formed respectively with two arc-surfaces, between the two end portions of the chain 10 is still defined a swaying clearance. The problem of the conventional chain 10 exists on the two end portions thereof. Since both end portions of the chain 10 are free, both end portions will random sway during the circulating motion, causing the interference to the rail of the rolling elements or to the patch portion.
FIG. 3 shows a chain 11 without end disclosed by JP Pat. No. H 11-294452. Two ends of the chain 11 are connected by engaging a fastening rod 111 on one end thereof with a fastening seat 112 on the other end thereof. In such a manner, though the problem that both end portions will sway random is avoided; the obvious problem of the chain 11 is that the non-degree of freedom link manner of the two end portions thereof cannot absorb the radial size variation caused by the shortening stress and stretching stress during the operation process of the chain 11.
FIG. 4 shows an integrally formed synchronous chain 12 without ends disclosed by JP Pat. No. 2,607,993. Though the conventional chain 12 is integrally formed to avoid the swaying problem caused by the end portions; the integral forming method is not very practical. The problem, which cannot be broke through, is that the synchronous chain 12 is difficult to design, to manufacture, to assemble and disassemble. Consequently, the technology is difficult to really apply and is quite difficult to carry out in mass production.
The aforementioned four categories of conventional technologies not only have their own inherent problems, and the chain is provided for bearing the pressure and rolling to eliminate the moving stress, thereby, the chain must reduce the most of the swaying motions of the ends during the movement, avoid the interference and absorb radial size variation, also the chain should consider the rationality of mass production, assembly and disassembly. However, various chains in the recent market still don't have the aforementioned effects.
In order to effectively solve the aforementioned problems, basing on the research and design technologies and experiences in the linear guideway field, the applicant of the present invention has eventually developed an original synchronous chain for a liner guideway from the angle of reasonable mass production and avoiding the interference.